People involved with highway traffic problems in this nation have long been concerned with the lack of communications on our expressways. Accidents and breakdowns present a special problem because of the limited exits and the lack of access to means of communication.
Many attempts have been made to solve this problem, including a phone system along the expressway and radio communications.
The short-comings with the phone system have been:
1. The cost of the system ($4,000 a mile capitalized cost plus $600 a year maintenance). PA1 2. Vandalism PA1 3. False alarms PA1 4. Accidents caused by people stopping along the expressway to use the phone PA1 5. Necessity to walk along expressway PA1 1. The crowded radio spectrum PA1 2. The powerful signal necessary to implement PA1 3. The constant transmission on Citizens Band with powerful transmitters PA1 4. The lack of sufficient mobile radio transmitter units available on the expressways
The short-comings of the radio communications have been:
Other systems such as electronic signalling through headlight beam flicking have met with so many false alarms they have been unworkable.
The following proposed system will hopefully cure, to a reasonable degree, all of the above described disadvantages.
Suitable systems, typical of those old in the art, suitable for utilization in performing applicant's method are: U.S. Pat. No. 3,631,484 Augenblick of 12/28/71; U.S. Pat. No. 3,747,068 Bruenr of 7/17/73; and U.S. Pat. No. 3,754,250 Bruner of 8/21/73. These patents disclose transceivers which receive from a unit predetermined set-up condition identifying information.
This system is composed of a series of transceivers spaced along the median or adjacent to the expressway. These transceivers will receive a coded message on one band, e.g., Citizens Band, and transmit on another band, e.g., Police Band. They will either be placed at regular intervals, e.g., every 10 miles, or at the proximity of each intersection of the expressway. Each transceiver will have two receiving antennas that are directional so that it can identify the direction of the trouble.
In addition to the transceivers, the system will utilize a large number of transmitters that will transmit, possibly on Citizens Band, a weak, coded signal of under 200 milliwatts. These transmitters will be designed to be installed in truck cabs, buses, and certain automobiles.
The simplest form of these transmitters would transmit a coded signal from the truck, etc. when the operator pushed a button. There would be probably a plurality of buttons, e.g., one button for accident and a second button for breakdown. In a less simple form, the transmitter would allow the truck driver to talk into a microphone after he had transmitted a coded signal that would activate the transceiver installed along the highway. To prevent vandalism, the transceiver would be mounted out of reach of the public, e.g., on a utility pole. The operator beeps at the stranded motorist a couple of times to signal him that he is going to send for help. If desirable the buttons on the transmitter could also activate an audible signal to the motorist.